Persistent race, ethnic, and socioeconomic disparities in preterm birth and low birth weight have been widely documented for decades, with important consequences for individual's lifelong health, social, and economic wellbeing. We still know little about why these disparities persist, but a recent surge of research across a number of disciplines aims to understand some of the mechanisms. My research will be one of the first to explore the pre-conception life course period and identify pre-conception risk factors from women's early life experiences. Findings from my research will be important for reducing preterm and low birth weight disparities by targeting pre-conception risk factors. My past and present research broadly examines how experiences in childhood affect women's health and social outcomes in adulthood. My dissertation topic is closely related to the present application as it leveraged life course theory to understand why married women are at lower risk of preterm birth and low birth weight relative to single and cohabiting women. This work produced new insights into life course processes (both inter-generational and intra-generational-through childhood, adolescence, and prenatal neighborhood environments) that put some women at greater risk of poor infant health. But strong racial-ethnic disparities remained, paving the way for the development of the current proposal. Thus far, my past training, mentoring, and research experience have drawn from sociology and demography to equip me with skills in theory and methods, and a knowledge base of the social mechanisms explaining effects of families-of-origin on health. This has set in motion my long-term career research program, which will examine how these social processes-across the preconception life course in childhood, adolescence, and the prenatal period-intersect with biologic or physiologic markers of stress reactivity to directly impact infant health. I hypothesize that this will shed new light on population-level infant health disparities that are highly stratified by social class and race-ethnicity. Thus far however, my training and research have focused solely on the social side; the K99/R00 will enable me to integrate biologic mechanisms that directly affect preterm birth or small-for-gestational age. I seek this K99/R00 Pathway to Independence Award to gain additional training and mentoring to expand my sociological study of families and health to a multi-disciplinary understanding of families and health. To do so, I need: (1) epidemiologic/public health training and mentoring in the etiology of infant health disparities and (2) multidisciplinary training and mentoring on the measurement of stress in the family and neighborhood environment. A rigorous training program will ensue including: formal training (participation in the NICHD-funded Reproductive, Perinatal, and Pediatric Epidemiology training program, formal coursework in perinatal epidemiology, attending a workshop on a premiere methodological strategy-non-hierarchical cross-classified multiple membership models, and attending a workshop on Bayesian analysis), hands-on research experience and collaboration (mentorship by social demographer and Add Health PI Dr. Kathleen Mullan Harris to learn how the social environment produces stress that bears on women's infant health outcomes and how biomarkers represent indicators of physiological disregulation due to this stress, mentorship by epidemiologist Dr. Anna Maria Siega-Riz to gain knowledge and skills in conceptualizing and measuring the stress response from an epidemiological perspective, collaboration with consultants Dr. Nancy Reichman and Dr. Julien Teitler to understand the etiology of infant health from clinical and public health perspectives, and participation in a working group led by mentor Dr. Paul Voss), and experience disseminating project findings (publishing and presenting findings at epidemiology, sociology, and demography conferences). By merging my primary expertise in sociology with new epidemiological, biomedical, and statistical knowledge that I will gain from this award, I will acquire a common language to communicate my findings to, and collaborate with, infant health scholars across disciplines. I will use this training to generate future hypotheses about how social environments (of the family and neighborhood) interact with biological systems to affect infant health, and in doing so, advance a cross-disciplinary research program on families and health. This award allows for training, mentoring, and protected research time necessary to achieve these goals. UNC is an ideal research environment to pursue these goals. CPC is a premiere population center and a leader in geospatial analyses and life course research; the Gillings School of Global Public Health is the #2 ranked school of public health in the country.